1. Field of the Invention
This invention relates broadly to surgical devices. More particularly, this invention relates to cross-fastened intramedullary implants for the fixation of bone fractures.
2. State of the Art
Severe long bone fractures are often treated with plating. In plating, a relatively large incision is made at the location of the fracture, musculature and tendons are displaced from the bone to expose the bone surface, and a bone plate is fixedly attached to one or more pieces of the fractured bone in a manner which, ideally, supports and stabilizes the fracture for healing. Due to the relatively invasive nature of the procedure required to implant the plate, plating is generally reserved for fractures which cannot be treated with a less invasive method of immobilization.
Less complicated fractures are often treated with casting or wires. However, such conservative treatment may not provide the stabilization and support necessary for desirable recovery. Yet, the operative procedure of plating is often too invasive for the relative non-severity of the fracture. Moreover, conventional plating can result in tendon irritation and skin necrosis, and may require extensive periosteal stripping in order to apply the plate on the bone surface. As such, many of the less displaced fractures, and particularly metaphyseal fractures (fractures at the end of the long bones), remain undertreated.
By way of example, a Colles"" fracture, which results from compressive forces being placed on the distal radius bone, and which causes backward displacement of the distal fragment and radial deviation of the hand at the wrist, is treated with a dorsal plate when there is a significant degree of displacement. However, a less-displaced Colles"" fracture is commonly undertreated due to the hesitancy of physicians to prescribe operative and invasive treatment. If not properly treated, such a fracture results in permanent wrist deformity. It is therefore important to align the fracture and fixate the bones relative to each other so that proper healing may occur.
In addition, there is no relatively minimally invasive procedure to treat fractures occurring at the metaphysis and that also provides the desired reduction and immobilization for such fractures.
Furthermore, there is no relatively minimally invasive procedure to treat distal radius fractures that provides the stability generally obtained by more invasive procedures, such as open reduction and internal fixation.
It is therefore an object of the invention to provide a relatively minimally invasive treatment which provides stabilization and support to long bone fractures.
It is another object of the invention to provide a relatively minimally invasive treatment which provides stabilization and support to metaphyseal fractures.
It is a further object of the invention to provide a implant which is fixedly held within the medullary canal of a long bone.
In accord with these objects, which will be discussed in detail below, a fixation system includes a device having a proximal nail portion and a distal plate portion, preferably horizontally and vertically offset relative to the nail portion by a neck portion. The nail portion includes a tapered end which is resilient, and a relatively rigid distal portion larger in diameter. For treatment of distal radius fractures, the distal portion of the nail portion preferably includes two threaded screw holes, and the plate portion has a low, narrow profile and includes three longitudinally displaced peg holes, each of which is adapted to orient a peg in a different orientation from the others. The plate portion also includes a threaded guide hole at which a guide can be stabilized with a screw in order to drill holes in alignment with the screw holes and pegs holes. The system also includes unicortical machine screws having a reasonably large head adapted to seat against the outer surface of the bone and a threaded shaft adapted to engage in the screw holes, and pegs adapted to engage in the peg holes.
In use, a relatively small incision is made in the skin, and the tapered end of the nail portion of the device is introduced percutaneously through the incision and through the fracture location into the medullary canal of the bone. The plate portion of the device is then maneuvered against a surface of the bone. The guide is coupled to the guide hole and the screw holes and peg holes are drilled. It is noted that the screw holes need only be drilled through the near side of the cortical bone, and not through the nail portion or the far side of the cortical bone.
The unicortical screws are then introduced through drilled holes and into the screw holes in the nail portion. The screws are tightened to pull the nail portion against the inner surface of the cortical bone. As the screws are tightened, the nail portion is pulled against the inner cortex and is automatically aligned with the axis of the bone. Thus, the plate portion is also thereby provided in a proper orientation for support of the metaphyseal area. In addition, as the screw heads are relative large, the bone is clamped between the screw heads and the nail portion. As a result, stability is increased. Alternatively, a combination of unicortical screws and bicortical screws can be used through the cortical screw holes.
The fracture at the metaphyseal portion of the bone is then reduced, and pegs are introduced through the drilled holes until the heads of the peg thread into the peg holes of the plate portion of the device. The pegs provide stabilization and support for subchondral fragments. Moreover, as the pegs preferably enter the subchondral fragments from a plurality of directions, additional fixation of the device into the bone is provided.
The fixation system permits a minimally invasive treatment of long bone fractures that may otherwise be undertreated. In addition, such fixation is very stable due to the clamping of the bone between the large screw heads and the device. Moreover, the large screw heads distribute the stress on the bone over a relatively large surface area on the outer surface of the cortical bone.
The fixation system can be adapted to treatment of fractures at multiple sites. For example, the distal radius, the proximal humerus, the distal femur, the proximal tibia, the distal tibia, and the hip are all suitable for application of the system of the invention.
Additional objects and advantages of the invention will become apparent to those skilled in the art upon reference to the detailed description taken in conjunction with the provided figures.